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Ruthenium

physical science Maturity 7-9 Next article →

Ruthenium is a rare transition metal with the symbol Ru and atomic number 44. It belongs to the platinum group, a set of metals known for being unreactive to most chemicals.

Ruthenium crystals
Ruthenium crystals

This stability makes it highly valuable for specialized industrial uses. While it is a hard, white metal, it is quite uncommon in nature. It is the 78th most abundant element in the Earth's crust. It exists in concentrations of about 100 parts per trillion. Because it is so rare, it is often extracted as a by-product of other mining operations.

Ruthenium is typically found as a minor component within platinum ores. Geologically, it appears in the Ural Mountains and across North and South America. It is also found in pyroxenite deposits in South Africa. Some commercially important amounts come from pentlandite in Sudbury, Ontario, Canada. The composition of these ores varies by location. For instance, platinum group metals from South Africa average 11% ruthenium. In contrast, those from the former USSR average only 2%.

Ruthenium crystals
Ruthenium crystals

Extracting the metal requires a complex chemical process. It is often recovered during the electrorefining of copper and nickel. During this process, noble metals precipitate as a substance called anode mud. To isolate ruthenium, scientists might use fusion with sodium peroxide. This is followed by dissolution in aqua regia, a mixture of acids. Ruthenium, osmium, and iridium are insoluble in aqua regia and precipitate out. Scientists then treat this residue with sodium oxide. This dissolves the ruthenium and osmium salts while leaving iridium behind. Finally, hydrogen is used to reduce ammonium ruthenium chloride into a metal powder or sponge.

History shows that ruthenium was discovered in 1844. The scientist Karl Ernst Claus found the element at Kazan State University. He was a Russian scientist of Baltic-German ancestry. Claus named the element in honor of Russia. He used the Latin name for Russia, which is Ruthenia. This naming tradition connects the element to its place of discovery. Since then, our understanding of its properties has grown significantly.

Ruthenium has several important physical and chemical characteristics. It is a polyvalent metal, meaning it can have many different oxidation states. These states range from -2 to +8. It is the only 4d transition metal that can reach the +8 oxidation state.

Tris(bipyridine)ruthenium(II)-chloride-powder
Tris(bipyridine)ruthenium(II)-chloride-powder

Physically, it is usually paramagnetic at room temperature. However, a specific thin film version can be ferromagnetic. It does not tarnish under normal conditions. It only oxidizes when it is heated. It is also used to improve other metals. Adding small amounts of ruthenium can increase the hardness of platinum and palladium. It also markedly increases the corrosion resistance of titanium.

In modern industry, ruthenium serves many vital roles. Most of the produced metal is used for wear-resistant electrical contacts. It is also used in thick-film resistors. A newer application involves semiconductor lithography. Here, it acts as a capping layer for extreme ultraviolet photomasks. This helps in the production of advanced computer chips. Ruthenium is also used as a chemical catalyst.

Grubbs catalyst Gen2
Grubbs catalyst Gen2

A famous example is Grubbs' catalyst, which is used in alkene metathesis reactions.

Polynbornene
Polynbornene

This process can be used to create different types of polymers.

Ruthenium also has a connection to nuclear science. It is found in spent nuclear fuel as a fission product. It can also be produced through nuclear transmutation. This involves exposing a target to strong neutron radiation. Naturally occurring ruthenium consists of seven stable isotopes. These include isotopes 96, 98, 99, 100, 101, 102, and 104. Scientists have also discovered 34 synthetic radioactive isotopes. Some of these, like 106Ru, are fission products of uranium or plutonium. Understanding these isotopes helps scientists manage nuclear materials and study the environment.

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🖼️ Images & Media (4)
File:Ruthenium crystals.jpg
Ruthenium crystals.jpg
File:Tris(bipyridine)ruthenium(II)-chloride-powder.jpg
Tris(bipyridine)ruthenium(II)-chloride-powder.jpg
File:Grubbs catalyst Gen2.svg
Grubbs catalyst Gen2.svg
File:Polynbornene.svg
Polynbornene.svg
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